In a glassware forming machine of I.S. type several components in each section are pneumatically operated and are mechanically connected to their respective linear actuators to achieve oscillatory motion of the component itself. Such components in a typical machine are; the "take-out" mechanism, which has tongs for lifting the newly formed ware from the final blow station to deposit them on a deadplate for transfer to a take away conveyor or the like; the "blowhead" or "baffle" which moves down onto the blank mold at the blank station after the gobs of molten glass have been delivered thereto to mate with the upwardly open blank mold cavities; the funnel mechanism which guides the gobs as they are dropped into these blank mold cavities; and the invert mechanism which moves the partially formed blanks or parisons from the blank station to a succeeding machine station for further forming.
Other examples might be listed for I.S. machine components which involve at least some oscillatory motion, and which are operated pneumatically from a linearly reciprocable actuator. With the demand for increased production rates in such machines, particularly in machines designed to handle "triple gobbing", the need for avoiding any abrupt starting and/or stopping of these components has become more apparent.
Prior art approaches have generally taken the form of decelerating the piston of the linear air actuator near the end of its stroke, U.S. Pat. No. 3,150,562 is an example of this solution. Still with reference to solving the problem by restricting the rate of flow of the compressible fluid itself, the recently issued U.S. Pat. No. 3,921,504 shows a similar solution, wherein the disadvantages of relying upon the air in the actuator itself are even more apparent.
Hydraulic snubbers have also been used in hydraulically operated actuators of the linear type, and U.S. Pat. No. 2,991,759 is an example of such a cushioning device, but in the I.S. machine environment the use of hydraulic snubbers to snub motion of a pneumatically operated machine component has usually taken the form of that shown in U.S. Pat. No. 3,147,105. These prior art hydraulic snubbers usually provide a constant snubbing force on the air driven component, unless a lost motion device is provided for rendering them less effective during a portion of their angular travel.
The chief aim of the present invention is to provide a self contained snubber, without external needle valves or the like, which snubber provides an ever increasing snubbing force toward the end of the mechanical motion, and which will operate in both directions if desired, or in an alternative embodiment will provide supplemental snubbing in one direction only.